Compensating draft gear



United States Patent 0 Ohio Filed Oct. 11, 1963, Ser. No. 315,452 9 Claims. (Cl. 213-45) This invention relates to draft gears of the so-called compensating, selective-travel type, having cushioning units separated for bringing into play a different number of units in draft than in buff action on a railway car equipped therewith.

The term compensating refers to capability resulting from construction of the draft gear enabling it to fit tightly between the forward and rear stops of a draft gear pocket, and also fit tightly against the front and rear surfaces defining the yoke opening. Ordinarily, this opening is terminated rearwardly by a forward facing yoke surface and forwardly by the rear end surface of the coupler butt. The term selective travel refers to operation of the gear wherein it is restricted to a shorter range of shortening or compression against one set of draft gear pocket stops, either front or rear, than against the other set. Usually, greater travel is desired in buff action wherein the gear undergoes shortening against the rear stops. Shorter travel is desired in draft since it is the'purpose to eliminate to a substantial extent the working of the gear under the draft forces incurred by train operation and thus to avoid wear of draft rigging parts.

The invention is induced primarily by a need for draft gears, particularly gears of the compensating type comprising rubber pads of greater foot-pound or work-absorbing capacity. For example, the present tendency to operate cars with greater load capacity has made apparent the inadequacy, under severe operating conditions, of gears of the prior art type illustrated in the accompanying drawing and illustrative of the best gears of that type commercially available. Increasing the work capacity of draft gears is made extremely diilicult by the rigid standardization of dimensions which is required by the transportation industry to be maintained in the car underframe and the various components of the draft rigging.

It is an essential object of the present invention to provide a railway draft gear of the compensating type, particularly, a gear which utilizes resilient pads, of greater work absorption capacity.

It is a further object in obtaining the above stated object to increase the work-absorption capacity of the draft gear under buff loads by providing construction by which the gear may attain greater range of travel or shortening range during buff action. Extension of bull travel will thus reduce the magnitude of forces created in the absorption of equal loads when compared with gears that provide shorter travel.

By thus increasing the buff travel it is a further object to reduce the wear and attrition on lading and railway car components, particularly the coupler and draft rigging system.

It is another object to provide draft gears of the compensating, selective-travel type of greater reserve capacity in order to avoid over-solid impact conditions incurred by gears of lesser capacity which result in vehicle and lading damage.

The invention, in brief, resides in' a draft gear which comprises at least two resilient cushioning units, typically including a group of rubber pads disposed in serial order in the longitudinal direction of the draft gear; a box type casing open at one end and having peripherally continuous side walls, such as four side walls integrally joined in rectangular arrangement, and an end wall at one extremity of the casing intermediately of the length of the 3,185,317 Patented May 25, 1965 gear. This casing contains one of the cushioning units. The gear further comprises a first follower, usually the front follower, disposed in the open end of the casing and held therein by detent means formed by the follower and the side walls in the assembled condition of the gear. The first follower is supported by the detent means against the cushioning unit to place the latter in a condition of slight initial compression. The gear includes a second follower spaced from the end wall of the casing to receive therebetween the other cushioning unit. The second follower, usually at the rear of the gear, is connected with the casing by means, such as bolts, which permit relative movement of the second follower and the casing toward one another within a maximum spacing which confines the other cushioning unit therebetween under a slight initial compression. The end wall of the casing is of a thickness held to a practical minimum requiring support against fracture that could result from full utilization of the load capacity of the cushioning unit located between the casing and the rear follower if the end wall was not supported by being joined to the side walls at at least four points uniformly angularly spaced about the longitudinal axis of the draft gear.

In the preferred embodiment including bolts for connecting the rear follower to the casing, the side walls of the casing have recesses immediately adjacent the end wall and the cushion contained in the casing is correspondingly notched or recessed contiguously with the recesses to receive portions of the bolts and to provide space for relative movement thereof within the outer contour of the casing.

In the accompanying drawing, with respect to which the invention is described:

FIG. 1 is a schematic plan view of coupler and draft rigging as mounted in the center sill of a railway car illustrating the draft gear of this invention as mounted for use;

FIG. 2 is a plan view of a draft gear of FIG. 1;

FIG. 3 is a side elevation, partly in section, of the draft gear of FIGS. 1 and 2;

FIG. 4 is an enlarged fragmentary plan view illustrating mode of connection of draft gear components;

FIG. 5 is an enlarged fragmentary side elevation of a rear corner portion of the gear as illustrated in FIG. 3;

FIG. 6 is a fragmentary enlarged elevation with a section broken away of an end portion of the draft gear of the previous figures which includes the open-end portion of the casing thereof;

FIG. 7 is a perspective View of a prior art draft gear showing quarter-sections of components removed; and

PEG. 8 is face view of a resilient pad from the casingenclosed cushioning unit of the gear illustrated by FIGS. 1 to 6.

This description and the accompanying drawing disclose a single embodiment of the invention as illustrated in FIGS. 1 to 6. FIG. 7 illustrates the closest known prior art draft gear 5 for the purpose of contrasting more sharply the improvements made in view of the standard pocket dimensions int-o which both the prior art gear and the improved gear 6 of FIGS. 1 to 6 must fit, the differences which contribute to the greater space available for cushioning media such as rubber pads, and the greater number of pads shown in the improved gear. Both the improved gear 6 of FIGS. 1 to 6 and the prior art gear of FIG. 7 are of compensating type. That is to say, the cushioning mechanism is actuated by two different cushioning units, one of which will maintain the normally rear front follower and the casing containing the other cushioning unit in contact with the rear and front stops, respectively. The other cushion enclosed by the casing reacts with the fixed wall of the casing and the usually front follower to maintain the front follower in engagement with the coupler butt, thereby causing the rear internal yoke surface to tightly engage the rear follower. This relationship of the draft gear with the stops, the yoke, and the coupler is shown in FIG. 1 wherein the draft gear 6 of this invention is shown in place in FIG. 1 between a pair of rear stops 8 and a pair of front stops 9. The draft gear is also positioned within a yoke 10 which receives the butt portion of coupler l1 pinned to a front portion of the yoke. The stops 3 and 9 are secured within a center sill 12 of the railway car in the conventional manner.

A compensating draft gear is normally oriented within the car underframe in order that more cushioning capacity of the draft gear may be brought into play from the buff action than under draft action. For example, the improved draft gear 6 comprises a first follower 14- which is normally its front follower; a front cushioning unit 15; a casing 17 which houses the cushioning unit 15 and receives the follower 14 within its front open end. The draft gear 6 further comprises a second follower 18, normally its rear follower; a cushioning unit if; and a pair of bolts 21, 22 which project through holes the-refor in the follower 1t and the rear end wall 24 of the casing 17. The bolts 21, 22 confine the cushioning unit 19 between the follower 18 and the end wall 24 and also provide lateral support and guidance to the individual pads 25 which constitute the unit 19. The bolts are further useful in maintaining the draft gear in a compactly assembled condition when removed from the draft gear pocket. This feature is of great advantage in removing the gear from or installing it in the center sill of a car.

With attention again to FIG. 1, surfaces 31 and 32 may be noted as seating against the rear stops 8. The front surfaces 33 and 34 of the casing seat against the front stops 9 at neutral condition of the draft gear. Seating of the rear follower l8 and the casing against the front and rear stops is established primarily by the initial compression of the cushioning unit 19.

However, the draft gear also fills the cavity circumscribed by the yoke 19 and the rear end surface of the coupler 11. Slack is eliminated in this cavity through operation of the cushion 15 in reacting against the rear wall 24 of the casing 17 and the front follower $14. To assure that this happens, the casing 17 has a pair of lugs 36 and 37 located in the extreme front open-end portion of the casing and spaced with respect to a rearwardfacing yoke-engaging surface 38 of the rear follower 18 to assure that the surface 33 will engage a rearward forward facing internal surface 3% of the yoke and that the forward facing face 41 of the front follower ldwill engage the rearward facing end surface 42 of the coupler butt while the casing and the rear follower also engage the forward and rear stops as hereinbefo-re explained. This condition will be established with a gap 44 existing between flanges 45 and 46 of the follower 14 which extend transversely into overlapping relation with rear facing surfaces of the lugs 36 and 37. The flanges 45 and 46 are constructed only as thick as needed to hold the front follower 17 against initial compression in the cushioning unit 15. By initial compression is meant that which is exerted by the unit 15 when, for example, the draft gear is removed from its pocket. The thickness of the flanges is retained as small as practical and the thickness of the front follower is also maintained at the lowest thickness which is practical for absorbing maximum buff forces applied to the draft gear between the coupler and the rear stops 8. Such an arrangement constitutes one way in which maximum space is established for the cushioning units within the confines of the draft gear. This purpose is further implemented by welding the lugs 36 and 37 into the casing as a final step in assembling the cushion 15 and the follower 14 within the casing 17 since it is impossible to enter the pads 63 into the casing otherwise than through the open front end thereof. In gen- 4. eral, structure of prior art compensating draft gears analogous to the casing 17 requires entry of a front follower and cushioning media through a side opening in such structure.

Another feature of the present draft gear 6 intended to maximize the space available for cushioning media is the relationship that exists in the peripherally continuous construction of its side walls 51, 52, 53, 54 and the end wall 24 of the casing. Because of the thinness of the end wall 24 desired in practising this invention, it is necessary to rely on the support against deformation in the end wall which occurs along the longitudinal axis of the gear by the stiffening effect on the end wall that results from rigid connection with the side walls substantially all along the outer extremity of the end wall. The relative thinness of the end-wall 24 is apparent when compared with the thickness of the analogous but relatively thick wall 24p of the nearest prior art draft gear, such as that shown in FIG. 7.

For example, such support is insufficient for the purpose of this invention when the casing comprises only two opposite side walls of conventional casing construction. The present invention is based in part on the provision of a box type casing having walls that are continuously joined throughout across section of the casing that is transverse to the longitudinal axis X-X of the draft gear. As one mode of expression, it may be stated that the end wall 24 is of a thickness which requires support against fracture by being joined to side walls of the casing at a minimum of four points uniformly angularly spaced about the longitudinal axis XX when the load exerted against the end wall 24 by the cushion 19 reaches :a predetermined load capacity through a pulling load applied by the coupler l1 and the yoke it It is not intended that the wall 24 be constructed to independently withstand loads in the range of the full loading capacity of the cushioning unit 19 without substantial reinforcement provided by integral juncture of the end wall with generally all portions of the adjacent ends of peripherally continuous side walls.

Another feature of the invention which is provided in a practical embodiment thereof is the use of guide and tie means, such as the bolts 21 and 22, and the provision for movement of portions of the bolts, i.e., the front portions as shown, past a rear portion of the cushion enclosed by the casing 17. This is a space-saving arrangement that is accomplished by a provision of recesses 56 and 57 defined in corner sections of the casing. The recesses 56,

57 are formed primarily by displacement of portions ofthe side walls adjacent the internal forward facing face of the wall 24. As shown, the recesses displace small corner portions of the wall 24 and are disposed in axial alignment with a pair of bolt holes 58 and 59 extending in the longitudinal direction of the draft gear through the end wall 24. The recesses 56, 57 longitudinally overlap the region for receiving the cushion 15. The rear follower 18 also has bolt holes 61 and 62 in axial alignment with the bolt holes 58 and 59 of the casing. The bolts 21 and 22 extend through the holes 58, 59, 61, 62 as shown. The rear follower 18 also has recesses 64 and 65 extending inwardly from its rearward facing surfaces 31 and 32 which permit some of the length of the bolts to be stored within these recesses as the follower 18 moves toward the casing end wall 24 under substantial buff or draft loads. The recesses 56, 57 of the casing and chamfered corners of the pads 68 which constitute the cushion 15 permit storage of portions of the bolts 21, 22 which slide into the recesses past pads 68 which are adjacent to the end wall 24. The pads 68, while of somewhat smaller periphery and dimensions transversely of the gear than the pads 25 of the cushion 19, are of generally similar construction wherein each comprises a stiff plate 69 of metal and a resilient cushion 71 disposed to a substantial extent within a smaller periphery than the plate, and in all cases, except the end pads of a cushion, on both sides of the plate. For

simplified design, manufacture, and assembly, the pads 25 and 68 are chamfered at all corners, and especially those corners which occur in alignment of the bolts 21 and 22 longitudinally of the draft gear.

In comparing the above described draft gear with the prior art device illustrated in FIG. 7, certain distinctions of the present invention are apparent which are believed typical of its advances over the prior art generally. Keeping in mind that the primary purpose was to substantially increase the work and force-absorption capacities of compensating type draft gears required to conform toa standard size draft gear pocket, it will be appreciated that greater room for cushioning media was essential. To reach this latter objective, it is obvious that the invention has been achieved primarily through a combination of structural changes embodied, e.g., (1) in an entirely different casing 17 incorporating continuous side walls and an unusually thin end wall, (2) the provision for movement of bolt portions past cushioning media contained therein, (3) unsually space-saving thinness and cooperating structure of the front follower and the casing to achieve more room for cushioning media in the front end of the casing, and (4) the provision of structure for securing the cushioning media within the casing after such media have been placed therein to thereby enable the use of peripherally continuous side walls.

The closest known prior draft gear is a rubber pad compensating selective gear Model No. MF-400-A manufactured by National Castings Company, of Cleveland, Ohio. This prior art gear contains 12 full pads; it has a maximum reserve work-absorption capacity of approximately 72,500 foot-pounds when impacted with a free-falling object developing 1,237,000 pounds of force in the gear. At work-absorption of 30,640 foot-pounds, this prior art gear is subjected to approximately 500,000 pounds of force.

The improved gear described herein which displaces the above described prior art gear, contains seventeen full pads and has a maximum work-absorption capacity tested to 93,000 foot-pounds by a free-falling object developing 237,000 pounds of force in the latter gear. Comparing again directly with the prior art gear, absorption of 72,500 and 30,640 foot-pounds by the improved gear only developed approximately 1,050,000 and 380,000 pounds of force, respectively, in the improved gear. The improved gear absorbs 38,000 foot-pounds when the falling test object develops 500,000 pounds of force therein. It is thus obvious that at all force levels, the improved draft gear has greater work absorption. Stated conversely, the improved gear is subjected to lower forces which, of course, are transmitted to the car and the lading thereof, at all humping or train operating conditions giving rise to buffing loads than the prior art draft gear with which it is compared above.

The terms and expressions which have been employed are used as terms of description and not of limitation and there is no intention of excluding such equivalents of the invention described or portions thereof as fall within the scope of the claims.

What is claimed is:

1. A railway car draft gear comprising:

(A) two cushioning units;

(B) a box-type casing having side walls disposed around a longitudinal axis of the gear in continu ous relationship along a transverse cross section of the gear, an end wall disposed intermediately of the gear and joining integrally with the side walls, an open end at one extremity of the gear, one of said units being disposed within the casing against said end wall;

(C) a first follower disposed in said open end in approximate engagement with the adjacent end of said one unit;

(D) detent means on said follower and said side walls adjacent said open end confining said follower there- 6 in with freedom to move toward said end wall in compressing said one unit;

(E) a second follower spaced from said end Wall with the other of said units disposed therebetween, said other unit being constructed to a predetermined compressive load capacity;

(F) means connecting the second follower with said casing at a predetermined maximum spacing confining said other unit therebetween; said means being slidable relative to the casing as the second follower moves within said maximum spacing;

(G) said end wall being of a thickness requiring support thereof against fracture under said load capacity by, and being joined integrally to, said side walls at at least four points substantially uniformly angularly spaced about said longitudinal axis.

2. The draft gear of claim 1 wherein:

said casing has a pair of lugs on opposite sides of said axis projecting from the inner periphery of the casing closely adjacent said open end; and

the first follower has recesses along opposite sides receiving said lugs, said recesses extending from the face of the follower exposed outwardly of the gear.

3. The draft gear of claim 1 wherein:

the casing has a pair of lugs disposed on opposite sides of said axis projecting theretoward from the inner periphery of the casing closely adjacent to said open end; and

said first follower has transversely extending flanges on opposite sides closely adjacent the face thereof dis posed inwardly of the casing in transversely overlapping relation with the lugs;

said flanges being of a thickness substantially no greater than that necessary for maintaining an initial compression of said one cushioning unit at neutral condition of the draft gear.

4. The draft gear of claim 1 wherein:

the sidewalls have peripherally opposite recesses opening along the junction thereof with said end wall, and the end wall has a pair of bolt holes contiguous with at least two of the recesses;

the second follower has bolt holes in longitudinal alignment with those of the end wall;

a pair of bolts extends through said bolt holes joining the casing and the second follower and define a maximum limit of spacing therebetween enabling the easing and the second follower to be movable toward each other within said limit to compress said other cushioning unit;

the bolts have portions received in said recesses having paths of movement therein in said longitudinal direction; and

said one cushioning unit is peripherally contoured to accommodate movement of said bolt portions lengthwise of the casing within the outer contour of the gear.

5. The draft gear of claim 4 wherein:

said detent means includes a pair of detachable lugs fixed to said side wall disposed on opposite sides of said axis and projecting theretoward from closely adjacent said front end; and the front follower has flanges on opposite sides adjacent its inwardly facing face extending transversely into overlapping relation with inward facing surfaces of the lugs;

said flanges have a thickness substantially no greater than that required to resist fracture in supporting the first follower against the initial compression of said one cushioning unit at neutral condition of the draft gear for maximizing the distance between said inward-facing follower face and said end wall.

6. The draft gear of claim 4 wherein:

the second follower has recesses extending inwardly from its outward facing face along the axes of its bolt holes;

said recesses being of a length to accommodate movement of the bolt portions received therein relative to the second follower;

the recesses of both the casing and the second follower having lengths which accommodate relative movement therein of respective bolt portions; and

each set of recesses accommodate, in part, movements of the bolts relative to the casing and the second follower in movements of the second follower toward the casing.

7. The draft gear of claim 5 wherein:

each cushioning unit consists of a plurality of pads disposed in serial order in the longitudinal direction of the draft gear;

the pads of said one unit have peripheries complementary to the inner periphery of the casing and indentations from such periphery which include paths of movement for said bolt portions received therein; and

the pads of said other unit have peripheries conforming substantially to the outer peripheries of the casing and the second follower except for indentations in the latter peripheries inwardly around bolt portions extending between the casing and the second follower.

8. The draft gear of claim 7 wherein:

cross sections of the casing and the gear transversely to said axis are generally rectangular;

each pad comprises a plate of rigid material defining said outer periphery of the pad, and a cushion of resilient material of generally lesser periphery; and

the plates of said pad are chamfered at corners in longitudinal alignment with said bolts.

9. The draft gear of claim 8 wherein:

said pads within the casing are insertable thereinto only through said open end; and

said lugs comprise small bars of metal and weld joints of metal securing the bars to the casing.

References Cited by the Examiner UNITED STATES PATENTS 2,907,474 10/59 Johnson 2l3-45 2,944,682 7/60 Willison 21345 LEO QUACKENBUSH, Primary Examiner. 

1. A RAILWAY CAR DRAFT GEAR COMPRISING: (A) TWO CUSHIONING UNITS; (B) A BOX-TYPE CASING HAVING SIDE WALLS DISPOSED AROUND A LONGITUDINAL AXIS OF THE GEAR IN CONTINUOUS RELATIONSHIP ALONG A TRANSVERSE CROSS SECTION OF THE GEAR, AN END WALL DISPOSED INTERMEDIATELY OF THE GEAR AND JOINING INTEGRALLY WITH THE SIDE WALLS, AN OPEN END AT ONE EXTREMITY OF THE GEAR, ONE OF SAID UNITS BEING DISPOSED WITHIN THE CASING AGAINST SAID END WALL; (C) A FIRST FOLLOWER DISPOSED IN SAID OPEN END IN APPROXIMATE ENGAGEMENT WITH THE ADJACENT END OF SAID ONE UNIT; (D) DETENT MEANS ON SAID FOLLOWER AND SAID SIDE WALLS ADJACENT SAID OPEN END CONFINING SAID FOLLOWER THEREIN WITH FREEDOM TO MOVE TOWARD SAID END WALL IN COMPRESING SAID ONE UNIT; 